Neisseria meningitidis and Neisseria gonorrhoeae are non-motile, gram negative diplococci that are pathogenic in humans.
Based on the organism's capsular polysaccharide, 12 serogroups of N. meningitidis have been identified. Group A is the pathogen most often implicated in epidemic disease in sub-Saharan Africa. Serogroups B and C are responsible for the vast majority of cases in the United States and in most developed countries. Serogroups W135 and Y are responsible for the rest of the cases in the United States and developed countries.
The meningococcal vaccine currently in use is a tetravalent polysaccharide vaccine composed of serogroups A, C, Y and W135. This approach cannot be used for Meningococcus B, however, because the menB capsular polysaccharide is a polymer of α(2–8)-linked N-acetyl neuraminic acid that is also present in mammalian tissue. One approach to a menB vaccine uses mixtures of outer membrane proteins (OMPs) To overcome the antigenic variability, multivalent vaccines containing up to nine different porins have been constructed [eg. Poolman (1992) Development of a meningococcal vaccine. Infect. Agents Dis. 4:13–28]. Additional proteins to be used in outer membrane vaccines have been the opa and opc proteins, but none of these approaches have been able to overcome the antigenic variability [eg. Ala'Aldeen & Borriello (1996) The meningococcal transferrin-binding proteins 1 and 2 are both surface exposed and generate bactericidal antibodies capable of killing homologous and heterologous strains. Vaccine 14(1):49–53].
A large number of Neisserial protein and nucleotide sequences are disclosed in WO99/24578, WO99/36544, WO99/57280 and WO00/22430. The contents of these four applications are incorporated herein by reference. Comprehensive sequence data from strain MC58 is disclosed in Tettelin et al. [Science (2000) 287:1809–1815], the contents of which are also incorporated herein by reference.